RUSTSEC-2023-0068: Sequential calls of encryption API (`encrypt`, `wrap`, and `dump`) result in nonce reuse

What to do

1. See which version you have: cargo tree -i cocoon (it also shows which of your dependencies pulls it in).
2. Update within your version requirement: cargo update -p cocoon. If the fix is a newer major or minor than your requirement allows, raise it in Cargo.toml (for example cocoon = "0.4.0") or update the dependency that pulls it in.
3. Check again with cargo audit, or paste your Cargo.lock into our Cargo.toml checker.

Details from the advisory

**Problem**: Trying to create a new encrypted message with the same cocoon object generates the same ciphertext. It mostly affects MiniCocoon and Cocoon objects with custom seeds and RNGs (where StdRng is used under the hood).

**Note**: The issue does **NOT** affect objects created with **Cocoon::new** which utilizes ThreadRng.

**Cause**: StdRng produces the same nonce because StdRng::clone resets its state.

**Measure**: Make encryption API mutable (encrypt, wrap, and dump).

**Workaround**: Create a new cocoon object with a new **seed** per each encryption.

How to Reproduce

let cocoon = MiniCocoon::from_password(b"password", &[1; 32]);
let mut data1 = "my secret data".to_owned().into_bytes();
let _ = cocoon.encrypt(&mut data1)?;

let mut data2 = "my secret data".to_owned().into_bytes();
let _ = cocoon.encrypt(&mut data2)?;

// data1: [23, 217, 251, 151, 179, 62, 85, 15, 253, 92, 192, 112, 200, 52]
// data2: [23, 217, 251, 151, 179, 62, 85, 15, 253, 92, 192, 112, 200, 52]

Workaround

For cocoon <= 0.3.3, create a new cocoon with a different **seed** per each encrypt/wrap/dump call.

let cocoon = MiniCocoon::from_password(b"password", &[1; 32]);
let mut data1 = "my secret data".to_owned().into_bytes();
let _ = cocoon.encrypt(&mut data1)?;

// Another seed: &[2; 32].
let cocoon = MiniCocoon::from_password(b"password", &[2; 32]);
let mut data2 = "my secret data".to_owned().into_bytes();
let _ = cocoon.encrypt(&mut data2)?;

// data1: [23, 217, 251, 151, 179, 62, 85, 15, 253, 92, 192, 112, 200, 52]
// data2: [53, 223, 209, 96, 130, 99, 209, 108, 83, 189, 123, 81, 19, 1]

References

• Package: crates.io/crates/cocoon
• Advisory: rustsec.org/advisories/RUSTSEC-2023-0068.html
• Report: github.com/fadeevab/cocoon/issues/22

From the RustSec Advisory Database (CC0-1.0) via the OSV export, downloaded Oct 24, 2026. Severity score computed from the published CVSS vector.